在setupBeforeClass之后有没有办法执行dataprovider函数？

I have a unit test class in which I want to instantiate a object from another class in order to that I used setUpBeforeClass() fixtures of phpunit. So if I will use that recently instantiated object directly in test function then its working fine.

If i'll use this object into another function which had been created for data providers. So that object sets to null cause providers always execute first.

Is there a way to call dataProviders just before the test runs, instead?

require_once('Dashboard.php');
Class Someclass extends PHPUnit_Framework_TestCase {

    protected static $_dashboard;
    public static function setUpBeforeClass()
    {
        self::$_dashboard = new Dashboard();
        self::$_dashboard->set_class_type('Member');
    }
    /**
     * Test Org Thumb Image Existense
     * param org profile image : array
     * @dataProvider getOrgProfileImages
     */
    public function testFieldValidation($a,$b){
        //If I call that object function here it will give the result.
        //$members = self::$_dashboard->get_members();
       //var_dump($members); Printing result as expected
        $this->assertTrue(true);
    }

    public function getOrgProfileImages() : array {
        //var_dump(self::$_dashboard);
        $members = self::$_dashboard->get_members();
        $tmp_array = ['2','2'];
        return $tmp_array;

    }

    public static function tearDownAfterClass()
    {

        self::$_dashboard = null;
    }
}

Error: The data provider specified for Someclass::testFieldValidation is invalid. Call to a member function get_members() on null

Please help to mitigate this issue.

Note: since I don't have the source of your Dashboard class, I'm using a random number in the examples below instead

Providers are invoked before any tests are run (and before any hooks, including beforeClass have a chance to run). By far the easiest way to achieve what you're after is to populate that static property on the class load:

use PHPUnit\Framework\TestCase;

/** @runTestsInSeparateProcesses enabled */
class SomeTest extends TestCase
{
    public static $_rand = null;

    public function provider()
    {
        $rand = self::$_rand;
        var_dump(__METHOD__, getmypid(), 'provided rand', $rand);
        return ['rand' => [$rand]];
    }

    /** @dataProvider provider */
    public function testSomething($rand)
    {
        $this->expectNotToPerformAssertions();
        var_dump(__METHOD__, getmypid(), 'tested with', $rand);
    }

    /** @dataProvider provider */
    public function testSomethingElse($rand)
    {
        $this->expectNotToPerformAssertions();
        var_dump(__METHOD__, getmypid(), 'tested with', $rand);
    }
}

// this runs before anything happens to the test case class
// even before providers are invoked

SomeTest::$_rand = rand();

Or you could instantiate you dashboard in the provider itself, on the first call:

public function provider()
{
    // Instantiate once
    if (null === self::$_rand) {
        self::$_rand = rand();
    }
    $rand = self::$_rand;
    var_dump(__METHOD__, getmypid(), 'provided rand', $rand);
    return ['rand' => [$rand]];
}

@dirk-scholten is right. You SHOULD be creating a new object for each test. It's a GOOD testing practice. Frankly it looks more like you are testing the data and not testing the code, which is fine I guess, it's just not the typical use of PHPUnit. Based on the assumption that you want to make sure every user in the database has a thumbnail image (just guessing), I would go with the following:

<?php

class DashboardDataTest extends PHPUnit\Framework\TestCase {

    private $dashboard;

    public function setUp() {
        $this->dashboard = new Dashboard();
    }

    /**
     * Test Org Thumb Image Existence
     * param org profile image : array
     *
     * @dataProvider getOrgProfileImages
     *
     * @param int $user_id
     */
    public function testThumbnailImageExists(int $user_id){

        $thumbnail = $this->dashboard->get_member_thumbnail($user_id);

        $this->assertNotNull($thumbnail);
    }

    public function geOrgUserIDs() : array {

        $dashboard            = new Dashboard();
        // Something that is slow
        $user_ids = $dashboard->get_all_the_member_user_ids();

        $data = [];

        foreach($user_ids as $user_id){
            $data[] = [$user_id];
        }

        return $data;
    }
}

Each data provider will get called once and only once before the tests. You do not need a static data fixture on the class because phpunit handles the data fixture for you when you use data providers.